Update x-issuer and x-jwks_uri flags (#302)
Update x-issuer and x-jwks_uri flags (#302)

Incorporate new prefix for x-issuer and x-jwks_uri flags. Stops gcloud throwing warnings when sample openapi.yaml is deployed.
JustinBeckwith/nodejs-docs-samples,GoogleCloudPlatform/nodejs-docs-samples,thesandlord/nodejs-docs-samples,JustinBeckwith/nodejs-docs-samples,JustinBeckwith/nodejs-docs-samples,GoogleCloudPlatform/nodejs-docs-samples,srijangulati/sierracartel,GoogleCloudPlatform/nodejs-docs-samples,GoogleCloudPlatform/nodejs-docs-samples,thesandlord/nodejs-docs-samples,srijangulati/sierracartel,srijangulati/sierracartel